Battery cell, battery, and electric device

Abstract

This application provides a battery cell, a battery, and an electrical device. The battery cell includes a casing, electrode terminals, an electrode assembly, and a current collector. The electrode terminals are disposed in the casing. The electrode assembly is housed within the casing, and a first tab is provided at the end of the electrode assembly facing the electrode terminals. The current collector is housed within the casing and disposed on the side of the first tab facing the electrode terminals. The current collector includes a first current collector portion and a second current collector portion connected to the first current collector portion. The first current collector portion is welded to the electrode terminals, and the second current collector portion is connected to the tab. The thickness of the first current collector portion is greater than the thickness of the second current collector portion.

Description

Battery cell, battery and electric device

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202421351283.X, filed on June 13, 2024, entitled “Battery cell, battery and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of battery, and more particularly, to a battery cell, a battery and an electric device. BACKGROUND

[0004] Battery cells are widely used in electronic devices, such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, electric tools, and the like.

[0005] In the development of battery technology, how to improve the reliability of battery cells is a research direction in battery technology.

[0006] SUMMARY

[0007] The present application provides a battery cell, a battery and an electric device, which can improve the reliability of the battery cell.

[0008] In a first aspect, the embodiments of the present application provide a battery cell, which includes a shell, an electrode terminal, an electrode assembly and a current collecting member. The electrode terminal is arranged in the shell. The electrode assembly is accommodated in the shell, and the electrode assembly is provided with a first tab at one end facing the electrode terminal. The current collecting member is accommodated in the shell and arranged at one side of the first tab facing the electrode terminal, and the current collecting member includes a first current collecting part and a second current collecting part connected to the first current collecting part. The first current collecting part is welded to the electrode terminal, and the second current collecting part is connected to the tab. The thickness of the first current collecting part is greater than that of the second current collecting part.

[0009] The second current collecting part has a smaller thickness relative to the first current collecting part, which can be deformed to adapt to the topography of the first tab, thereby reducing the gap between the second current collecting part and the first tab and improving the connection strength between the current collecting member and the first tab. The first current collecting part has a greater thickness relative to the second current collecting part, and the first current collecting part is not easy to be melted through when welding the first current collecting part to the electrode terminal, thereby reducing the risk of poor welding and improving the connection strength between the first current collecting part and the electrode terminal. The use of the first current collecting part with a greater thickness can improve the current carrying capacity between the current collecting member and the electrode terminal.

[0010] In some embodiments, the second current collecting part is arranged around the first current collecting part, so as to increase the contact area between the second current collecting part and the first tab and improve the current carrying capacity.

[0011] In some embodiments, the first current collecting part is welded to the electrode terminal and forms a first welding part. In the thickness direction of the current collecting member, the size of the part of the first welding part formed on the first current collecting part is smaller than the thickness of the first current collecting part. When the current collecting member and the first current collecting part are welded, the first current collecting part is not melted through, so as to improve the welding effect.

[0012] In some embodiments, in the thickness direction of the current collecting member, the size of the part of the first welding part formed on the first current collecting part is greater than the thickness of the second current collecting part. The first welding part has a large penetration in the thickness direction, so as to improve the connection strength between the current collecting member and the electrode terminal and the current carrying capacity.

[0013] In some embodiments, the Brinell hardness of the second current collecting part is higher than the Brinell hardness of the first current collecting part. The second current collecting part has a higher hardness than the first current collecting part, so as to reduce the risk of damage and deformation of the second current collecting part during the production, transportation and the like of the current collecting member.

[0014] In some embodiments, the thickness of the first current collecting part is 1.2-3 times the thickness of the second current collecting part, so as to improve the connection strength between the first current collecting part and the electrode terminal and the current carrying capacity and reduce the loss of the energy density of the battery cell caused by thickening the first current collecting part.

[0015] In some embodiments, at least part of the first current collecting part protrudes from the surface of the second current collecting part facing the electrode terminal and abuts against the electrode terminal. The first current collecting part protrudes from the second current collecting part towards the electrode terminal, so as to reduce the risk of contact between the second current collecting part and the electrode terminal, thereby avoiding the interference of the second current collecting part with the contact between the first current collecting part and the electrode terminal to a certain extent.

[0016] In some embodiments, in the thickness direction of the current collecting member, the second current collecting part is arranged to be spaced apart from the electrode terminal, so as to reduce the risk of interference of the second current collecting part with the contact between the first current collecting part and the electrode terminal.

[0017] In some embodiments, the side of the electrode terminal facing the current collecting member is provided with a first recess, and at least part of the first current collecting part is accommodated in the first recess and abuts against the bottom surface of the first recess. The first recess can accommodate at least part of the first current collecting part, so as to reduce the space occupied by the electrode terminal and the current collecting member in the thickness direction, provide space utilization, and improve the energy density of the battery cell. When the electrode terminal and the current collecting member are assembled, the first recess can also position the first current collecting part, so as to reduce the assembly difficulty and improve the assembly efficiency.

[0018] In some embodiments, in the thickness direction of the current collecting member, the height of the first current collecting portion protruding from the surface of the second current collecting portion facing the electrode terminal is 1.2-2 times the depth of the first recess. Defining the ratio of the height to the depth to be greater than or equal to 1.2 can keep a gap between the second current collecting portion and the electrode terminal, reducing over-positioning. Defining the ratio of the height to the depth to be less than or equal to 2 can reduce space waste and improve space utilization.

[0019] In some embodiments, in the radial direction of the current collecting member, a gap is provided between the first current collecting portion and the side surface of the first recess. In the radial direction of the current collecting member, the first current collecting portion and the first recess are in clearance fit, thereby reducing the difficulty of inserting the first current collecting portion into the first recess and reducing metal particles generated by friction between the first current collecting portion and the electrode terminal.

[0020] In some embodiments, the side of the electrode terminal facing away from the current collecting member is provided with a second recess, and the electrode terminal includes a connecting portion located at the bottom of the second recess, the connecting portion being welded with the first current collecting portion and forming a first welding portion, and the first welding portion being exposed to the second recess. By providing the second recess on the electrode terminal, the thickness of the connecting portion can be reduced, thereby reducing the welding power required for welding the connecting portion with the first current collecting portion, reducing heat generation, reducing the risk of burning other components, and improving the reliability of the battery cell.

[0021] In some embodiments, the side of the electrode terminal facing the current collecting member is provided with a first recess, and the bottom surface of the first recess and the bottom surface of the second recess form a connecting portion. At least part of the first current collecting portion is accommodated in the first recess. The first recess can accommodate at least part of the first current collecting portion, thereby reducing the space occupied by the electrode terminal and the current collecting member in the thickness direction and providing space utilization. By providing the first recess and the second recess on both sides of the electrode terminal, the thickness of the connecting portion can be reduced, and the welding power required for welding the connecting portion with the first current collecting portion can be reduced.

[0022] In some embodiments, the first current collecting portion has a top surface abutting the bottom surface of the first recess. In the thickness direction of the current collecting member, the bottom surface of the second recess at least partially overlaps the top surface, and the projection of the outer periphery of the bottom surface of the second recess is located within the projection of the top surface. When the battery cell is discharging, the current is transmitted outward through the connecting portion and the side wall of the second recess; by arranging the first welding portion close to the outer periphery of the bottom surface of the second recess, the distance between the first welding portion and the side wall of the second recess can be reduced, thereby shortening the conduction path and improving the overcurrent capacity. The projection of the outer periphery of the bottom surface of the second recess is located within the projection of the top surface, which can reduce the risk of the molten pool extending outside the top surface when welding close to the outer periphery of the bottom surface of the second recess, reduce the risk of false welding, and improve the welding strength.

[0023] In some embodiments, the diameter of the top surface is greater than the diameter of the bottom surface of the second recess. The difference between the diameters of the top surface and the bottom surface of the first recess is less than the difference between the diameters of the top surface and the bottom surface of the second recess. The first current collecting portion can be in a clearance fit with the first recess, and the difference between the diameters of the top surface and the bottom surface of the first recess is related to the position of the first current collecting portion in the radial direction. By setting the diameter relationship among the top surface, the bottom surface of the first recess, and the bottom surface of the second recess, the outer periphery of the bottom surface of the second recess can be prevented from exceeding the outer periphery of the top surface, thereby reducing the risk of false welding.

[0024] In some embodiments, the thickness of the connecting portion is 1-3 times the thickness of the first current collecting portion. By limiting the ratio of the thickness of the connecting portion to the thickness of the first current collecting portion to be greater than or equal to 1, the penetration depth of the first welding portion can be increased, and the connection strength and the overcurrent capacity between the connecting portion and the first current collecting portion can be improved. By limiting the ratio of the thickness of the connecting portion to the thickness of the first current collecting portion to be less than or equal to 3, the welding power required for welding the connecting portion and the first current collecting portion can be reduced, the heat generation can be reduced, the risk of burning other components can be reduced, and the reliability of the battery cell can be improved.

[0025] In some embodiments, the connecting portion is provided with a first through hole, and the first current collecting portion is provided with a second through hole. The first through hole and the second through hole are oppositely arranged in the thickness direction of the current collecting member. The battery cell further comprises a first sealing member, at least a portion of the first sealing member is arranged in the second recess and is used to seal the first through hole.

[0026] The first through hole and the second through hole can be used to communicate the internal space of the shell with the external space of the shell during the production process of the battery cell. For example, the first through hole and the second through hole can be used to inject electrolyte, and can also be used to exhaust during the formation process. The first sealing member can be used to seal the first through hole, so as to reduce the risk of external impurities entering the internal space of the shell through the first through hole and the second through hole, and improve the reliability of the battery cell. The second recess can accommodate at least a portion of the first sealing member, thereby improving the space utilization.

[0027] In some embodiments, in the radial direction of the current collecting member, the hole wall of the first through hole protrudes inwardly from the hole wall of the second through hole. The first sealing member comprises a first sealing portion, a second sealing portion, and a third sealing portion. The first sealing portion is located on the outer side of the connecting portion, the second sealing portion is located on the inner side of the connecting portion and is at least partially accommodated in the second through hole, and the third sealing portion is accommodated in the first through hole and connects the first sealing portion and the second sealing portion. In the thickness direction of the current collecting member, a portion of the connecting portion is located between the first sealing portion and the second sealing portion. The connecting portion can limit the third sealing portion in the radial direction of the first through hole, and also limit the first sealing portion and the second sealing portion in the thickness direction, thereby fixing the first sealing member and reducing the risk of the first sealing member falling off the connecting portion. The second through hole is larger than the first through hole in the radial direction, thereby providing space for the second sealing portion and facilitating the overlap of the second sealing portion and the connecting portion in the thickness direction.

[0028] In some embodiments, the second sealing portion is spaced apart from the hole wall of the second through hole in the radial direction of the current collecting member. The embodiments of the present application can reduce the risk of the first sealing member extruding the first current collecting portion when assembling the first sealing member, and reduce the deformation of the current collecting member.

[0029] In some embodiments, the surface of the first current collecting portion facing the first tab is in abutment with the first tab, and the surface of the second current collecting portion facing the first tab is in abutment with the first tab. The abutment of the first current collecting portion and the second current collecting portion with the first tab can increase the contact area of the current collecting member with the first tab and improve the flow area between the current collecting member and the first tab.

[0030] In some embodiments, the surface of the first current collecting portion facing the first tab is flush with the surface of the second current collecting portion facing the first tab, which can improve the uniformity of the stress on the first tab, reduce stress concentration, and reduce the risk of local collapse of the first tab.

[0031] In some embodiments, the first current collecting portion protrudes from the surface of the second current collecting portion facing the first tab. The surface of the first tab facing the current collecting member is provided with a tab groove, and a portion of the first current collecting portion is accommodated in the tab groove. The protruding arrangement of the first current collecting portion towards the first tab can increase the thickness of the first current collecting portion, and the tab groove can provide space for the first current collecting portion, thereby reducing the space occupied by the first current collecting portion and improving the space utilization.

[0032] In some embodiments, the current collecting member comprises a protruding portion and a third recess portion, the second current collecting portion surrounds the protruding portion, the protruding portion protrudes from the surface of the second current collecting portion facing the electrode terminal, and the third recess portion is in position corresponding to the protruding portion and is recessed relative to the surface of the second current collecting portion facing the first tab. The bottom wall of the third recess portion is the first current collecting portion.

[0033] The arrangement of the protruding portion and the third recess portion can increase the overall strength of the current collecting member and reduce the deformation of the current collecting member during production and transportation. The arrangement of the third recess portion can also space the first current collecting portion apart from the first tab, reduce the heat conducted to the first tab during welding of the first current collecting portion and the electrode terminal, reduce the risk of deformation and shrinkage of the insulating member of the electrode assembly due to heat, and improve the reliability of the battery cell.

[0034] In some embodiments, the current collecting member comprises a protruding portion and a third recess portion, the second current collecting portion surrounds the protruding portion, the protruding portion protrudes from the surface of the second current collecting portion facing the electrode terminal, and the third recess portion is in position corresponding to the protruding portion and is recessed relative to the surface of the second current collecting portion facing the first tab. The current collecting member further comprises a current collecting plate accommodated in the third recess portion, and the current collecting plate is fixed to the bottom wall of the third recess portion. The first current collecting portion comprises the current collecting plate and the bottom wall of the third recess portion.

[0035] The current collector plate can play a protection role when welding the electrode terminal and the bottom wall of the third recess. Even if the bottom wall of the third recess is melted through, the current collector plate can stop the molten liquid and be used for welding, so as to reduce the risk of molten liquid falling. The current collector plate is independently formed with the bottom wall of the third recess, which can reduce the forming difficulty of the third recess and the convex part. The current collector plate is accommodated in the third recess, which can also improve the space utilization.

[0036] In some embodiments, the housing includes a shell having an opening and an end cap covering the opening. The shell includes an end wall opposite the end cap, and the electrode terminal is disposed on the end wall.

[0037] In some embodiments, the first tab is wound, and a portion of the first tab is bent to form an overlapping area overlapping in the axial direction of the electrode assembly. The overlapping area is welded to the second current collecting part. The overlapping area of the first tab has a multi-layer structure. Welding the overlapping area to the second current collecting part can not only reduce the risk of false welding, but also increase the welding area of the first tab and the second current collecting part, thereby improving the overcurrent capacity. The second current collecting part has a small thickness, which can be deformed to adapt to the overlapping area, thereby reducing the gap between the second current collecting part and the first tab and reducing the risk of false welding.

[0038] In a second aspect, the embodiments of the present application provide a battery including a plurality of the battery cells provided by any of the embodiments of the first aspect.

[0039] In a third aspect, the embodiments of the present application provide a use electric device including the battery provided by any of the embodiments of the second aspect, and the battery is used to provide electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0041] FIG. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0042] FIG. 2 is an exploded schematic diagram of a battery provided by some embodiments of the present application;

[0043] FIG. 3 is a structural schematic diagram of a battery module shown in FIG. 2;

[0044] FIG. 4 is a structural schematic diagram of a battery cell provided by some embodiments of the present application;

[0045] FIG. 5 is an exploded schematic diagram of the battery cell shown in FIG. 4;

[0046] FIG. 6 is a cross-sectional schematic diagram of the battery cell shown in FIG. 4;

[0047] Fig. 7 is an enlarged view of the circle frame of Fig. 6;

[0048] Fig. 8 is an enlarged view of the square frame A of Fig. 7;

[0049] Fig. 9 is a cross-sectional view of an electrode terminal of a battery cell according to some embodiments of the present application;

[0050] Fig. 10 is a cross-sectional view of a current collecting member of a battery cell according to some embodiments of the present application;

[0051] Fig. 11 is a partially cross-sectional view of a battery cell according to other embodiments of the present application;

[0052] Fig. 12 is a partially cross-sectional view of a battery cell according to yet other embodiments of the present application;

[0053] Fig. 13 is a partially cross-sectional view of a battery cell according to further other embodiments of the present application;

[0054] Fig. 14 is a schematic view of an electrode assembly and a current collecting member of a battery cell according to still other embodiments of the present application, before assembly.

[0055] Reference signs are explained as follows:

[0056] 1: vehicle; 2: battery; 3: controller; 4: motor; 5: case; 5a: first case portion; 5b: second case portion; 5c: accommodation space; 6: battery module; 7: battery cell;

[0057] 10: electrode assembly; 11: main body portion; 12: first tab; 121: tab recess; 122: overlap region; 13: second tab;

[0058] 20: housing; 21: case; 211: end wall; 212: side wall; 22: end cap;

[0059] 30: electrode terminal; 31: first recess; 311: bottom surface of first recess; 312: side surface of first recess; 32: second recess; 321: bottom surface of second recess; 33: connecting portion; 331: first through-hole;

[0060] 40: current collecting member; 41: first current collecting portion; 411: top surface; 412: second through-hole; 42: second current collecting portion; 43: protruding portion; 44: third recess; 45: side portion; 46: current collecting plate;

[0061] 50: first seal; 51: first sealing portion; 52: second sealing portion; 53: third sealing portion;

[0062] 60: second seal;

[0063] W, first weld; Z, thickness direction. DETAILED DESCRIPTION

[0064] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0065] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the description of the specification and claims of the present application and the above description of the drawings are intended to cover the non-exclusive inclusion. The terms "first", "second" and the like in the description of the specification and claims of the present application or the above description of the drawings are used to distinguish different objects, not to describe a particular order or primary and secondary relationship.

[0066] In the present application, the phrase "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments.

[0067] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0068] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " in the present application generally represents a "or" relationship between the front and rear associated objects.

[0069] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length, width, and other dimensions of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0070] “Multiple” appearing in the present application means two or more (including two).

[0071] In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging the battery cell.

[0072] The battery cell can be a lithium ion battery cell, a sodium ion battery cell, a sodium lithium ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium sulfur battery cell, a magnesium ion battery cell, a nickel hydrogen battery cell, a nickel cadmium battery cell, a lead storage battery cell, etc., and the present application is not limited thereto.

[0073] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode and a negative electrode. During the charging and discharging of the battery cell, active ions (e.g., lithium ions) are inserted and extracted between the positive electrode and the negative electrode.

[0074] In some embodiments, the electrode assembly includes a separator disposed between the positive electrode and the negative electrode, which can prevent the positive and negative electrodes from short-circuiting while allowing the active ions to pass through.

[0075] In some embodiments, the positive electrode can be a positive electrode sheet, which can include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0076] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction thereof, and the positive electrode active material is disposed on either one or both of the opposite surfaces of the positive electrode current collector.

[0077] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, silver surface treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, etc. can be used. The composite current collector can include a high molecular material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a high molecular material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0078] As an example, the positive active material can include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive active material can also be used. These positive active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (may also be referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxide can include, but are not limited to, at least one of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (may also be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (may also be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (may also be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (may also be referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (may also be referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2), and modified compounds thereof, etc.

[0079] In some embodiments, the positive electrode can employ a foamed metal or a foamed carbon. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. When the foamed metal is used as the positive electrode, the foamed metal surface can not be provided with a positive active material, or of course can be provided with a positive active material. As an example, the foamed metal can also be filled or / and deposited with a lithium source material, a potassium metal, or a sodium metal, the lithium source material being a lithium metal and / or a lithium-rich material.

[0080] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative electrode current collector.

[0081] As an example, the negative current collector can employ a metal foil, a foamed metal, a foamed carbon, or a composite current collector. For example, as the metal foil, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, a carbon, nickel, or titanium, or the like can be employed. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or the like. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, or the like) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0082] As an example, the negative electrode sheet can include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0083] As an example, the negative current collector has two surfaces opposite in the thickness direction thereof, and the negative active material is disposed on either one or both of the two opposite surfaces of the negative current collector.

[0084] As an example, the negative active material can employ a negative active material for a battery cell known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, lithium titanate, or the like. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative active material can also be used. These negative active materials can be used alone only one or in combination of two or more.

[0085] In some embodiments, the material of the positive current collector can be aluminum, and the material of the negative current collector can be copper.

[0086] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0087] In some embodiments, the separator is a separator film. The present application does not particularly limit the type of the separator film, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0088] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0089] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0090] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0091] Liquid electrolytes include electrolyte salts and solvents.

[0092] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0093] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0094] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0095] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0096] As an example, the polymer solid-state electrolyte can be a polyether (polyethylene oxide), a polysiloxane, a polycarbonate, a polyacrylonitrile, a polyvinylidene fluoride, a polymethyl methacrylate, a single-ion polymer, a polyionic liquid-lithium salt, a cellulose, or the like.

[0097] As an example, the inorganic solid-state electrolyte can be one or more of an oxide solid-state electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), a sulfide solid-state electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorous sulfide, argyrodite), amorphous sulfide), and a halide solid-state electrolyte, a nitride solid-state electrolyte, and a hydride solid-state electrolyte.

[0098] As an example, the composite solid-state electrolyte is formed by adding an inorganic solid-state electrolyte filler to a polymer solid-state electrolyte.

[0099] In some embodiments, the electrode assembly is in a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound into the jelly-roll structure.

[0100] In some embodiments, the electrode assembly is in a stack structure.

[0101] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be provided, and the plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately stacked.

[0102] As an example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet is folded to form a plurality of folded segments that are stacked.

[0103] As an example, the positive electrode sheet and the negative electrode sheet are both folded to form a plurality of folded segments that are stacked.

[0104] As an example, a plurality of separators can be provided, and each of the plurality of separators is provided between any adjacent positive electrode sheet or negative electrode sheet.

[0105] As an example, the separators can be provided continuously and are provided between any adjacent positive electrode sheet or negative electrode sheet by folding or winding.

[0106] In some embodiments, the electrode assembly can have a shape of a cylindrical shape, a flat shape, or a polygonal shape.

[0107] In some embodiments, the electrode assembly can be provided with a tab. The tab can guide current out of the electrode assembly. The tab can include a positive tab and a negative tab.

[0108] In some embodiments, the battery cell can include a housing. The housing can be used to encapsulate the electrode assembly and other components such as the electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film, or the like.

[0109] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes, the prismatic battery cell including a square battery cell, a blade battery cell, a multi-prismatic battery cell, for example, a hexagonal battery cell, etc., without specific limitation in the present application.

[0110] The battery referred to in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0111] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0112] In some embodiments, the battery can be a battery pack, and the battery pack includes a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0113] In some embodiments, the box body can be part of the chassis structure of the vehicle. For example, part of the box body can be at least part of the floor of the vehicle, or part of the box body can be at least part of the cross beam and longitudinal beam of the vehicle.

[0114] In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0115] In some embodiments, the battery cell is also provided with an electrode terminal for electrically connecting to the tab of the electrode assembly to realize the charging and discharging of the electrode assembly. In order to facilitate assembly and improve the overcurrent capacity of the battery cell, the electrode assembly tab and the electrode terminal are usually connected by a current collecting member.

[0116] The current collecting member usually has a small thickness, so that when the current collecting member and the tab are assembled, the current collecting member is easy to deform to adapt to the topography of the tab, thereby reducing the gap between the current collecting member and the tab and improving the connection strength of the current collecting member and the tab. When the current collecting member and the electrode terminal are welded, the current collecting member may be melted through due to the small thickness, thereby causing poor welding; in addition, the use of a small-thickness current collecting member also affects the overcurrent capacity between the current collecting member and the electrode terminal.

[0117] In view of this, the embodiments of the present application provide a technical scheme, which increases the thickness of the local current collecting member to reduce the risk of the current collecting member being melted through when welded with the electrode terminal and improve the overcurrent capacity between the current collecting member and the electrode terminal.

[0118] The battery cell described in the embodiments of the present application is suitable for a battery and an electric device using the battery.

[0119] The battery cell and the battery disclosed by the embodiments of the present application can be used in a power consumption device using the battery as a power source or a variety of energy storage systems using the battery as an energy storage element. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy, an electric aircraft toy, and the like; and the spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, and the like.

[0120] The following embodiments are described by taking a vehicle as an example for convenience of description.

[0121] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application.

[0122] As shown in FIG. 1, a vehicle 1 is internally provided with a battery 2, which can be arranged at the bottom, the head or the tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as an operating power source of the vehicle 1.

[0123] The vehicle 1 can further include a controller 3 and a motor 4, the controller 3 being used to control the battery 2 to supply power to the motor 4, for example, to meet the power demand of the vehicle 1 during starting, navigation and driving.

[0124] In some embodiments of the present application, the battery 2 can not only be used as an operating power source of the vehicle 1, but also be used as a driving power source of the vehicle 1, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1.

[0125] FIG. 2 is an exploded schematic diagram of a battery according to some embodiments of the present application. As shown in FIG. 2, the battery 2 includes a box body 5 and a battery cell (not shown in FIG. 2), and the battery cell is accommodated in the box body 5.

[0126] The box body 5 is used to accommodate the battery cell, and the box body 5 can have various structures. In some embodiments, the box body 5 can include a first box body part 5a and a second box body part 5b, the first box body part 5a and the second box body part 5b are mutually covered, and the first box body part 5a and the second box body part 5b jointly define an accommodation space 5c for accommodating the battery cell. The second box body part 5b can be a hollow structure with one end open, and the first box body part 5a is a plate-shaped structure, which is covered on the open side of the second box body part 5b to form the box body 5 with the accommodation space 5c; or the first box body part 5a and the second box body part 5b can both be a hollow structure with one side open, and the open side of the first box body part 5a is covered on the open side of the second box body part 5b to form the box body 5 with the accommodation space 5c. Of course, the first box body part 5a and the second box body part 5b can have various shapes, such as a cylinder, a cuboid, and the like.

[0127] To improve the sealing performance of the first box body part 5a and the second box body part 5b after being connected, a sealing member such as sealing glue, a sealing ring, or the like can be arranged between the first box body part 5a and the second box body part 5b.

[0128] The first box body part 5a can also be referred to as an upper box cover, and the second box body part 5b can also be referred to as a lower box body, assuming that the first box body part 5a is covered on the top of the second box body part 5b.

[0129] In the battery 2, the battery cell can be one or multiple. If the battery cell is multiple, the multiple battery cells can be connected in series, in parallel, or in a mixed manner. The mixed manner means that the multiple battery cells are connected in series and in parallel. The multiple battery cells can be directly connected in series, in parallel, or in a mixed manner, and then the whole of the multiple battery cells is accommodated in the box body 5. Of course, the multiple battery cells can be first connected in series, in parallel, or in a mixed manner to form a battery module 6, and then the multiple battery modules 6 are connected in series, in parallel, or in a mixed manner to form a whole and are accommodated in the box body 5.

[0130] The battery cell can be the smallest unit of the battery.

[0131] FIG. 3 is a structural schematic diagram of the battery module shown in FIG. 2.

[0132] In some embodiments, as shown in FIG. 3, the battery cell 7 is multiple, and the multiple battery cells 7 are first connected in series, in parallel, or in a mixed manner to form a battery module 6. Then, the multiple battery modules 6 are connected in series, in parallel, or in a mixed manner to form a whole and are accommodated in the box body.

[0133] The multiple battery cells 7 in the battery module 6 can be electrically connected through a busbar component to realize the parallel connection, the series connection, or the mixed connection of the multiple battery cells 7 in the battery module 6. The busbar component can be one or multiple, and each busbar component is used to electrically connect at least two battery cells.

[0134] FIG. 4 is a structural schematic diagram of a battery cell provided in some embodiments of the present application; FIG. 5 is an exploded schematic diagram of the battery cell shown in FIG. 4; FIG. 6 is a cross-sectional schematic diagram of the battery cell shown in FIG. 4; FIG. 7 is an enlarged schematic diagram of a circle frame in FIG. 6; FIG. 8 is an enlarged schematic diagram of a square frame A in FIG. 7; FIG. 9 is a cross-sectional schematic diagram of an electrode terminal of the battery cell provided in some embodiments of the present application; and FIG. 10 is a cross-sectional schematic diagram of a current collecting member of the battery cell provided in some embodiments of the present application.

[0135] Referring to FIGS. 4 to 10, the present embodiments provide a battery cell 7, which includes an outer shell 20 and an electrode assembly 10, and at least part of the electrode assembly 10 is accommodated in the outer shell 20.

[0136] The housing 20 is a hollow structure, and an accommodation space for accommodating the electrode assembly 10 and the electrolyte is formed inside the housing 20. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cuboid structure, a cuboid housing can be selected; if the electrode assembly 10 is a cylindrical structure, a cylindrical housing can be selected.

[0137] As an example, the housing 20 includes a shell 21 having an opening and an end cap 22 for covering the opening.

[0138] The shell 21 is a component for cooperating with the end cap 22 to form an internal cavity of the battery cell 7, and the internal cavity formed can be used to accommodate the electrode assembly 10, the electrolyte and other components.

[0139] The shell 21 and the end cap 22 can be independent components. As an example, an opening can be provided on the shell 21, and the end cap 22 is used to cover the opening to form the internal cavity of the battery cell 7.

[0140] The shell 21 can be various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. In particular, the shape of the shell 21 can be determined according to the specific shape and size of the electrode assembly 10. The material of the shell 21 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the present application does not make special limitations on this.

[0141] The shape of the end cap 22 can be adapted to the shape of the shell 21 to cooperate with the shell 21. The material of the end cap 22 can be the same as or different from the material of the shell 21. Alternatively, the end cap 22 can be made of a material with certain hardness and strength (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easy to deform when subjected to extrusion and collision, so that the battery cell 7 can have higher structural strength and reliability performance can also be improved.

[0142] The end cap 22 is connected to the shell 21 by welding, bonding, clamping or other means.

[0143] The shell 21 can be open at one end or both ends. In some examples, the shell 21 can be a structure open on one side, and the end cap 22 is provided as one and covers the shell 21. In other examples, the shell 21 can also be a structure open on both sides, and the end cap 22 is provided as two, and the two end caps 22 cover the two openings of the shell 21 respectively.

[0144] The electrode assembly 10 is a component in which an electrochemical reaction occurs in the battery cell 7. One or more electrode assemblies 10 can be contained in the shell 21.

[0145] In some embodiments, the electrode assembly 10 includes a main body portion 11, a first tab 12, and a second tab 13. One of the first tab 12 and the second tab 13 is a positive tab, and the other is a negative tab.

[0146] As an example, the electrode assembly 10 includes a positive tab and a negative tab. The positive tab and the negative tab have portions with active material that constitute the main body portion 11 of the electrode assembly 10, and portions without active material that constitute the positive tab and the negative tab. The positive tab and the negative tab can be located together at one end of the main body portion 11 or at two ends of the main body portion 11, respectively.

[0147] During charging and discharging of the battery, the positive active material and the negative active material react with the electrolyte.

[0148] In some embodiments, the battery cell 7 includes an electrode terminal 30 disposed on the outer shell 20. The electrode terminal 30 can serve as an output electrode of the battery cell 7 for connection to an external circuit. The electrode terminal 30 is configured to be connected to a busbar to achieve electrical connection between the battery cells 7.

[0149] The electrode terminal 30 can be disposed on the housing 21 or on the end cap 22.

[0150] The electrode terminal 30 can be one or multiple.

[0151] In some examples, the electrode terminal 30 is one, and the electrode terminal 30 is electrically connected to the first tab 12. Optionally, at least a portion of the outer shell 20 can be electrically connected to the second tab 13. The electrode terminal 30 and the outer shell 20 can serve as two output electrodes of the battery cell 7, respectively.

[0152] In other examples, the electrode terminal 30 is two, and the two electrode terminals 30 are electrically connected to the first tab 12 and the second tab 13, respectively. The two electrode terminals 30 can serve as two output electrodes of the battery cell 7, respectively.

[0153] The electrode terminal 30 can be disposed on the housing 21 in an insulating manner or electrically connected to the housing 21, as long as the first tab 12 and the second tab 13 are prevented from being electrically connected.

[0154] In some embodiments, the battery cell 7 further includes a current collecting member 40 that electrically connects the first tab 12 to the electrode terminal 30.

[0155] In some embodiments, the battery cell 7 includes a housing 20, an electrode terminal 30, an electrode assembly 10, and a current collecting member 40. The electrode terminal 30 is disposed on the housing 20. The electrode assembly 10 is accommodated in the housing 20, and the electrode assembly 10 is provided with a first tab 12 at an end facing the electrode terminal 30. The current collecting member 40 is accommodated in the housing 20 and disposed on a side of the first tab 12 facing the electrode terminal 30, and the current collecting member 40 includes a first current collecting portion 41 and a second current collecting portion 42 connected to the first current collecting portion 41, the first current collecting portion 41 is welded to the electrode terminal 30, and the second current collecting portion 42 is connected to the tab, the thickness of the first current collecting portion 41 is greater than the thickness of the second current collecting portion 42.

[0156] The second current collecting portion 42 can be connected to the first tab 12 by welding, abutting, bonding, or other means to achieve electrical connection between the current collecting member 40 and the first tab 12.

[0157] The arrangement of the first current collecting portion 41 and the second current collecting portion 42 can be flexibly set as needed. In some examples, the second current collecting portion 42 is disposed around the first current collecting portion 41; in other examples, the first current collecting portion 41 is disposed around the second current collecting portion 42; in yet other examples, the second current collecting portion 42 is a plurality, and the plurality of second current collecting portions 42 are disposed along the circumference of the first current collecting portion 41 and connected to the outer periphery of the first current collecting portion 41.

[0158] The first current collecting portion 41 and the second current collecting portion 42 can be integrally formed, or independently formed and connected by welding or other means.

[0159] The Brinell hardness of the second current collecting portion 42 can be higher than, equal to, or lower than the Brinell hardness of the first current collecting portion 41.

[0160] The ratio of the thickness of the first current collecting portion 41 to the thickness of the second current collecting portion 42 is greater than 1. Exemplarily, the ratio of the thickness of the first current collecting portion 41 to the thickness of the second current collecting portion 42 is 1.1, 1.2, 1.5, 2, 2.5, 3, 3.5, 4, or 5.

[0161] The second current collecting portion 42 can be in contact with the electrode terminal 30, or can not be in contact with the electrode terminal 30. The first current collecting portion 41 can be in contact with the first tab 12, or can not be in contact with the first tab 12.

[0162] In the embodiments of the present application, the second current collecting portion 42 has a smaller thickness relative to the first current collecting portion 41, which can be deformed to adapt to the topography of the first tab 12, thereby reducing the gap between the second current collecting portion 42 and the first tab 12 and improving the connection strength between the current collecting member 40 and the first tab 12. The first current collecting portion 41 has a larger thickness relative to the second current collecting portion 42, and the first current collecting portion 41 is less likely to be melted through when welding the first current collecting portion 41 and the electrode terminal 30, thereby reducing the risk of poor welding and improving the connection strength between the first current collecting portion 41 and the electrode terminal 30. The use of the first current collecting portion 41 with a larger thickness can improve the overcurrent capacity between the current collecting member 40 and the electrode terminal 30.

[0163] Compared with the scheme of thickening the current collecting member 40 as a whole, the embodiments of the present application can also reduce the space and weight occupied by the current collecting member 40 and improve the energy density of the battery monomer 7.

[0164] In some embodiments, the electrode terminal 30 and the current collecting member 40 are welded from the electrode terminal side when assembling the electrode terminal 30 and the current collecting member 40.

[0165] Illustratively, laser can be irradiated on the electrode terminal 30 to achieve welding of the electrode terminal 30 and the first current collecting portion 41.

[0166] In some embodiments, the first current collecting portion 41 and the second current collecting portion 42 do not overlap in the thickness direction Z of the current collecting member 40. The thickness of the first current collecting portion 41 and the thickness of the second current collecting portion 42 do not overlap in the thickness direction Z, thereby reducing the maximum size of the current collecting member 40 in the thickness direction Z.

[0167] In some embodiments, the first tab 12 and the second current collecting portion 42 are welded.

[0168] Illustratively, the welding of the first tab 12 and the second current collecting portion 42 is laser welding. When welding the first tab 12 and the second current collecting portion 42, laser can be irradiated on the second current collecting portion 42, and a part of the second current collecting portion 42 and a part of the first tab 12 are fused together. The second current collecting portion 42 needs to be melted through by laser, and the second current collecting portion 42 with a smaller thickness is easy to melt through, thereby reducing the requirement for welding power.

[0169] In some embodiments, at least part of the first current collecting portion 41 overlaps the electrode terminal 30 in the thickness direction Z of the current collecting member 40.

[0170] In some embodiments, the shell 21 includes an end wall 211 opposite the end cover 22, and the electrode terminal 30 is arranged on the end wall 211.

[0171] In some embodiments, the first current collecting part 41 has a projection in the thickness direction Z which is circular, square, triangular, polygonal or other shape.

[0172] In some embodiments, the end wall 211 is electrically connected to the second tab 13, and the electrode terminal 30 is insulated and arranged on the end wall 211. The end wall 211 and the electrode terminal 30 can serve as two output poles of the battery cell 7; the end wall 211 and the electrode terminal 30 are located on the same side of the electrode assembly 10, facilitating the connection of the plurality of battery cells 7 into a group by the current collecting member.

[0173] In some embodiments, the shell 21 further comprises a side wall 212 which surrounds the electrode assembly 10 and is integrally formed with the end wall 211. The side wall 212 is connected to the end cover 22.

[0174] In some embodiments, the battery cell 7 is a cylindrical battery cell, and the side wall 212 has a cylindrical structure; alternatively, the battery cell 7 is a square battery cell, and the side wall 212 has a square cylindrical structure.

[0175] In some embodiments, the second tab 13 is electrically connected to the end wall 211 through the side wall 212. Alternatively, the side wall 212 is electrically connected to the end cover 22, and the second tab 13 is electrically connected to the end wall 211 through the end cover 22 and the side wall 212.

[0176] In some embodiments, the second current collecting part 42 is arranged around the first current collecting part 41, which can increase the connection area between the second current collecting part 42 and the first tab 12 and improve the overcurrent capacity.

[0177] The first current collecting part 41 has a large thickness and is located in the middle of the current collecting member 40, which can improve the rigidity of the current collecting member 40 as a whole and reduce the deformation of the current collecting member 40 during production or transportation.

[0178] In some embodiments, the first current collecting part 41 is welded to the electrode terminal 30 and forms a first welding part W.

[0179] The first welding part W can be one or multiple.

[0180] The first welding part W can be a dot-shaped welding mark or a linear welding mark. The first welding part W can be a straight line-shaped welding mark or a curved line-shaped welding mark.

[0181] In some embodiments, the second current collecting part 42 is welded to the first tab 12 and forms a second welding part (not shown).

[0182] In some embodiments, in the thickness direction Z of the current collecting member 40, the size h1 of the part of the first welding part W formed on the first current collecting part 41 is smaller than the thickness t1 of the first current collecting part 41.

[0183] When the current collecting member 40 and the first current collecting portion 41 are welded, the first current collecting portion 41 is not melted through, improving the welding effect.

[0184] In some embodiments, in the thickness direction Z of the current collecting member 40, the first welding portion W is spaced apart from the surface of the first current collecting portion 41 facing the first tab 12. Exemplarily, in the thickness direction Z of the current collecting member 40, the spacing between the first welding portion W and the surface of the first current collecting portion 41 facing the first tab 12 is t1-h1.

[0185] In the process of welding the electrode terminal 30 and the first current collecting portion 41, the molten liquid is less likely to fall to the electrode assembly 10, thereby reducing the risk of the electrode assembly 10 being burned and improving the reliability of the battery monomer 7.

[0186] In some embodiments, in the thickness direction Z of the current collecting member 40, the size h1 of the portion of the first welding portion W formed on the first current collecting portion 41 is greater than the thickness t2 of the second current collecting portion 42.

[0187] The first welding portion W has a large penetration in the thickness direction Z, thereby improving the connection strength and overcurrent capacity between the current collecting member 40 and the electrode terminal 30.

[0188] In some embodiments, the Brinell hardness of the second current collecting portion 42 is higher than that of the first current collecting portion 41. In the process of production, transportation, etc. of the current collecting member 40, the current collecting member 40 may be damaged or deformed due to extrusion by other structures. In the embodiments of the present application, although the second current collecting portion 42 is thinner than the first current collecting portion 41, the second current collecting portion 42 has a higher hardness than the first current collecting portion 41, which can reduce the risk of damage or deformation of the second current collecting portion 42.

[0189] The thickness t1 of the first current collecting portion 41 is 1.2-3 times the thickness t2 of the second current collecting portion 42. Optionally, t1 / t2 is 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.1, 2.3, 2.5, 2.7, 2.9 or 3.

[0190] The embodiments of the present application limit t1 / t2 to be greater than or equal to 1.2, to reduce the risk of the first current collecting portion 41 being melted through during welding, and to improve the connection strength and overcurrent capacity between the first current collecting portion 41 and the electrode terminal 30. The embodiments of the present application limit t1 / t2 to be less than or equal to 3, to reduce the space and weight occupied by the first current collecting portion 41, and to reduce the loss of energy density of the battery monomer 7 caused by thickening the first current collecting portion 41.

[0191] In some embodiments, t1 is 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.7 mm, or 0.8 mm.

[0192] In some embodiments, t2 is 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, or 0.4 mm.

[0193] In some embodiments, at least part of the first current collecting portion 41 protrudes from the surface of the second current collecting portion 42 facing the electrode terminal 30 and abuts against the electrode terminal 30.

[0194] The first current collecting portion 41 protrudes from the second current collecting portion 42 toward the electrode terminal 30 to reduce the risk of the second current collecting portion 42 contacting the electrode terminal 30, thereby avoiding, to some extent, the second current collecting portion 42 interfering with the contact between the first current collecting portion 41 and the electrode terminal 30.

[0195] In some embodiments, the second current collecting portion 42 is spaced apart from the electrode terminal 30 in the thickness direction Z of the current collecting member 40, thereby reducing the risk of the second current collecting portion 42 interfering with the contact between the first current collecting portion 41 and the electrode terminal 30.

[0196] In some embodiments, the gap between the second current collecting portion 42 and the electrode terminal 30 in the thickness direction Z is greater than or equal to 0.2t2.

[0197] In some embodiments, the side of the electrode terminal 30 facing the current collecting member 40 is provided with a first recess 31, and at least part of the first current collecting portion 41 is accommodated in the first recess 31 and abuts against the bottom surface 311 of the first recess.

[0198] The first recess 31 has a depth h2. Exemplarily, h2 can be the maximum dimension of the first recess 31 in the thickness direction Z of the current collecting member 40.

[0199] In the thickness direction Z of the current collecting member 40, the height of the surface of the first current collecting portion 41 protruding from the surface of the second current collecting portion 42 facing the electrode terminal 30 is h3. Exemplarily, h3 is greater than or equal to h2.

[0200] Exemplarily, in the radial direction of the current collecting member 40, the first recess 31 and the first current collecting portion 41 can be a tight fit, a clearance fit, or a transition fit.

[0201] The first recess 31 can accommodate at least part of the first current collecting portion 41, thereby reducing the space occupied by the electrode terminal 30 and the current collecting member 40 in the thickness direction Z, providing space utilization, and improving the energy density of the battery cell 7. When assembling the electrode terminal 30 and the current collecting member 40, the first recess 31 can also position the first current collecting portion 41, thereby reducing the assembly difficulty and improving the assembly efficiency.

[0202] In some embodiments, in the thickness direction Z of the current collecting member 40, the height h3 of the first current collecting portion 41 protruding from the surface of the second current collecting portion 42 facing the electrode terminal 30 is 1.2-2 times the depth h2 of the first recess 31.

[0203] Optionally, h3 / h2 is 1.2, 1.3, 1.5, 1.6, 1.8, or 2.

[0204] Limiting h3 / h2 to be greater than or equal to 1.2 can keep a gap between the second current collecting portion 42 and the electrode terminal 30, reducing over-positioning. Limiting h3 / h2 to be less than or equal to 2 can reduce space waste and improve space utilization.

[0205] In some embodiments, in the radial direction of the current collecting member 40, a gap is provided between the first current collecting portion 41 and the side surface 312 of the first recess.

[0206] In the radial direction of the current collecting member 40, the first current collecting portion 41 and the first recess 31 are in clearance fit, thereby reducing the difficulty of inserting the first current collecting portion 41 into the first recess 31 and reducing metal particles generated by friction between the first current collecting portion 41 and the electrode terminal 30.

[0207] In some embodiments, the side of the electrode terminal 30 facing away from the current collecting member 40 is provided with a second recess 32, and the electrode terminal 30 includes a connecting portion 33 at the bottom of the second recess 32, the connecting portion 33 is welded with the first current collecting portion 41 and forms a first welding portion W, and the first welding portion W is exposed to the second recess 32.

[0208] The second recess 32 can be a cylindrical recess, a conical recess, a stepped recess, or a recess of other shapes.

[0209] The connecting portion 33 corresponds to at least part of the bottom surface 321 of the second recess. The bottom surface 321 of the second recess can be a plane or a curved surface, and optionally, the bottom surface 321 of the second recess is a plane perpendicular to the thickness direction Z.

[0210] During welding, laser is irradiated on the connecting portion 33 from the outside; part of the connecting portion 33 and part of the first current collecting portion 41 are melted and form a molten pool, and the molten pool solidifies to form the first welding portion W. The first welding portion W has a welding surface exposed to the second recess 32, and the welding surface is uneven compared to the bottom surface 321 of the second recess.

[0211] By opening the second recess 32 on the electrode terminal 30, the thickness of the connecting portion 33 can be reduced, thereby reducing the welding power required for welding the connecting portion 33 and the first current collecting portion 41, reducing heat generation, reducing the risk of burning other components, and improving the reliability of the battery cell 7.

[0212] In some embodiments, the electrode terminal 30 is provided with a first recess 31 on the side facing the current collecting member 40, and a second recess 32 on the side away from the current collecting member 40, and a connecting portion 33 is formed between the bottom surface 311 of the first recess and the bottom surface 321 of the second recess. At least part of the first current collecting portion 41 is accommodated in the first recess 31.

[0213] Exemplarily, in the thickness direction Z, the bottom surface 311 of the first recess and the bottom surface 321 of the second recess at least partially overlap. The area where the bottom surface 311 of the first recess and the bottom surface 321 of the second recess overlap in the thickness direction Z defines the connecting portion 33.

[0214] The bottom surface 311 of the first recess can be greater than, equal to, or less than the bottom surface 321 of the second recess.

[0215] The first recess 31 can accommodate at least part of the first current collecting portion 41, thereby reducing the space occupied by the electrode terminal 30 and the current collecting member 40 in the thickness direction Z, and providing space utilization. By providing the first recess 31 and the second recess 32 on both sides of the electrode terminal 30, the thickness of the connecting portion 33 can be reduced, and the welding power required for welding the connecting portion 33 and the first current collecting portion 41 can be reduced.

[0216] In some embodiments, the first current collecting portion 41 has a top surface 411 abutting the bottom surface 311 of the first recess. In the thickness direction Z of the current collecting member 40, the bottom surface 321 of the second recess at least partially overlaps the top surface 411, and the projection of the outer periphery of the bottom surface 321 of the second recess is located within the projection of the top surface 411.

[0217] The top surface 411 of the first current collecting portion 41 can be circular, circular ring-shaped, polygonal, or other shapes. The bottom surface 311 of the first recess can be circular, circular ring-shaped, polygonal, or other shapes.

[0218] When the battery cell 7 is discharging, the current is transmitted outward through the connecting portion 33 and the side wall of the second recess 32. By arranging the first welding portion W close to the outer periphery of the bottom surface 321 of the second recess, the distance between the first welding portion W and the side wall of the second recess 32 can be reduced, thereby shortening the conductive path and improving the overcurrent capacity. The projection of the outer periphery of the bottom surface 321 of the second recess is located within the projection of the top surface 411, and when welding is performed close to the outer periphery of the bottom surface 321 of the second recess, the risk of the molten pool extending outside the top surface 411 can be reduced, the risk of false welding can be reduced, and the welding strength can be improved.

[0219] In some embodiments, the outer periphery of the top surface 411 exceeds the outer periphery of the bottom surface 321 of the second recess in the radial direction of the current collecting member 40. The portion of the top surface 411 that exceeds the bottom surface 321 of the second recess in the radial direction can serve as a redundant design to reduce the risk of false welding caused by assembly errors.

[0220] In some embodiments, the diameter of the top surface 411 is greater than the diameter of the bottom surface 321 of the second recess. The difference in diameter between the bottom surface 311 of the first recess and the top surface 411 is less than the difference in diameter between the top surface 411 and the bottom surface 321 of the second recess.

[0221] Exemplarily, the top surface 411 can be a circular ring or a circle. If the top surface 411 is a circular ring, the diameter of the top surface 411 is the outer diameter of the top surface 411.

[0222] Exemplarily, the bottom surface 321 of the second recess can be a circular ring or a circle. If the bottom surface 321 of the second recess is a circular ring, the diameter of the top surface 411 is the outer diameter of the top surface 411.

[0223] Exemplarily, the bottom surface 311 of the first recess can be a circular ring or a circle. If the bottom surface 311 of the first recess is a circular ring, the diameter of the top surface 411 is the outer diameter of the top surface 411.

[0224] The diameter of the bottom surface 311 of the first recess is greater than or equal to the diameter of the top surface 411.

[0225] The first current collecting portion 41 can be in clearance fit with the first recess 31, and the difference in diameter between the bottom surface 311 of the first recess and the top surface 411 is related to the position of the first current collecting portion 41 in the radial direction. By setting the diameter relationship between the top surface 411, the bottom surface 311 of the first recess, and the bottom surface 321 of the second recess, the outer periphery of the bottom surface 321 of the second recess can not exceed the outer periphery of the top surface 411, thereby reducing the risk of false welding.

[0226] In some embodiments, the top surface 411 can also be a curved surface, for example, the top surface 411 is a circular arc surface.

[0227] In some embodiments, the thickness t3 of the connecting portion 33 is 1-3 times the thickness t1 of the first current collecting portion 41.

[0228] Optionally, t3 / t1 is 1, 1.5, 2, 2.5, or 3.

[0229] By limiting t3 / t1 to be greater than or equal to 1, the penetration of the first weld W can be increased, and the connection strength and the overcurrent capacity between the connection portion 33 and the first current collecting portion 41 can be improved. By limiting t3 / t1 to be less than or equal to 3, the welding power required for welding the connection portion 33 and the first current collecting portion 41 can be reduced, the heat generation can be reduced, the risk of burning other components can be reduced, and the reliability of the battery cell 7 can be improved.

[0230] In some embodiments, the connection portion 33 is provided with a first through hole 331, and the first current collecting portion 41 is provided with a second through hole 412. The first through hole 331 and the second through hole 412 are oppositely arranged along the thickness direction Z of the current collecting member 40.

[0231] Along the thickness direction Z of the current collecting member 40, the first through hole 331 and the second through hole 412 at least partially overlap.

[0232] The diameter of the first through hole 331 can be greater than, less than, or equal to the diameter of the second through hole 412.

[0233] Exemplarily, the first through hole 331 extends from the bottom surface 321 of the second recess to the bottom surface 311 of the first recess. The bottom surface 311 of the first recess is an annular surface provided for the first through hole 331, and the bottom surface 321 of the second recess is an annular surface provided for the first through hole 331.

[0234] In some embodiments, the first through hole 331 and the second through hole 412 can be used to inject electrolyte into the housing 20.

[0235] In some embodiments, the battery cell 7 further comprises a first sealing member 50. At least a portion of the first sealing member 50 is arranged in the second recess 32 and is used to seal the first through hole 331.

[0236] The first through hole 331 and the second through hole 412 can be used to communicate the internal space of the housing 20 with the external space of the housing 20 during the production of the battery cell 7. For example, the first through hole 331 and the second through hole 412 can be used to inject electrolyte, and can also be used to exhaust during the formation process. The first sealing member 50 can be used to seal the first through hole 331, so as to reduce the risk of external impurities entering the internal space of the housing 20 through the first through hole 331 and the second through hole 412, and improve the reliability of the battery cell 7. The second recess 32 can accommodate at least a portion of the first sealing member 50, thereby improving the space utilization.

[0237] In some embodiments, in the radial direction of the current collecting member 40, the hole wall of the first through hole 331 protrudes inwardly from the hole wall of the second through hole 412.

[0238] Exemplarily, the diameter of the first through hole 331 is less than the diameter of the second through hole 412.

[0239] In some embodiments, the first seal 50 includes a first sealing portion 51, a second sealing portion 52, and a third sealing portion 53. The first sealing portion 51 is located outside the connecting portion 33. The second sealing portion 52 is located inside the connecting portion 33 and at least partially accommodated in the second through hole 412. The third sealing portion 53 is accommodated in the first through hole 331 and connects the first sealing portion 51 and the second sealing portion 52. In the thickness direction Z of the current collecting member 40, a portion of the connecting portion 33 is located between the first sealing portion 51 and the second sealing portion 52.

[0240] The connecting portion 33 can limit the third sealing portion 53 in the radial direction of the first through hole 331, and also limit the first sealing portion 51 and the second sealing portion 52 in the thickness direction Z, so as to fix the first seal 50 and reduce the risk of the first seal 50 falling off the connecting portion 33. The second through hole 412 is larger than the first through hole 331 in the radial direction, so as to provide space for the second sealing portion 52 and facilitate the overlap of the second sealing portion 52 and the connecting portion 33 in the thickness direction Z.

[0241] For example, the second sealing portion 52 can be in contact with the hole wall of the second through hole 412, or can not be in contact with the hole wall of the second through hole 412.

[0242] In some embodiments, the first sealing portion 51 is in contact with the bottom surface 321 of the second recess. The second sealing portion 52 is in contact with the bottom surface 311 of the first recess.

[0243] In some embodiments, the second sealing portion 52 does not overlap the first current collecting portion 41 in the thickness direction Z. The embodiments of the present application can reduce the size of the first seal 50 in the thickness direction Z.

[0244] In some embodiments, the second sealing portion 52 is spaced apart from the hole wall of the second through hole 412 in the radial direction of the current collecting member 40.

[0245] The embodiments of the present application can reduce the risk of the first seal 50 extruding the first current collecting portion 41 when assembling the first seal 50, and reduce the deformation of the current collecting member 40.

[0246] In some embodiments, the third sealing portion 53 is in interference fit with the first through hole 331.

[0247] In some embodiments, the first seal 50 is made of an elastic material. For example, the material of the first seal 50 is rubber.

[0248] In some embodiments, the first welding portion W does not overlap the first sealing portion 51 in the thickness direction Z. The embodiments of the present application can reduce the risk of the first welding portion W bruising the first sealing portion 51.

[0249] In some embodiments, the first welding portion W surrounds the first sealing portion 51.

[0250] In some embodiments, the first seal 50 is configured to be installed to the connecting portion 33 before the welding of the connecting portion 33 and the first current collecting portion 41. When welding, the first seal 50 can seal the first through hole 331, reduce the risk of metal particles generated by welding falling into the electrode assembly 10 through the first through hole 331, and improve reliability.

[0251] In some embodiments, the diameter D of the second through hole 412 is 1 to 10 times the thickness t2 of the second current collecting portion 42. Defining D / t2 to be greater than or equal to 1 can improve the electrolyte injection efficiency and reduce the deformation of the current collecting member 40 during the injection process of the electrolyte. Defining D / t2 to be greater than or equal to 10 can reduce the loss of the flow area of the current collecting member 40.

[0252] In some embodiments, the battery cell 7 further includes a second seal 60 located outside the first welding portion W, connecting the electrode terminal 30 and used for sealing the second recess 32.

[0253] The second seal 60 can protect the first welding portion W from the outside, reducing the risk of corrosion of the first welding portion W.

[0254] In some embodiments, at least part of the second seal 60 is accommodated in the second recess 32, thereby improving the space utilization and reducing the maximum size of the battery cell 7.

[0255] In some embodiments, the second seal 60 is fixed to the side wall of the second recess 32.

[0256] In some embodiments, the second seal 60 is welded to the side wall of the second recess 32.

[0257] In some embodiments, the side wall of the second recess 32 is provided with a stepped surface, and the second seal 60 abuts against the stepped surface. The stepped surface can support the second seal 60.

[0258] In some embodiments, the first seal 50 and the second seal 60 are spaced apart in the thickness direction Z of the current collecting member 40.

[0259] In some embodiments, the electrode terminal 30 is used for direct connection to the current collecting member, for example, the electrode terminal 30 is used for welding with the current collecting member. Alternatively, the second seal 60 is an electrically conductive member, and the electrode terminal 30 is connected to the current collecting member through the second seal 60, and the second seal 60 can be used for welding with the current collecting member.

[0260] In some embodiments, the surface of the first current collecting portion 41 facing the first tab 12 abuts against the first tab 12, and the surface of the second current collecting portion 42 facing the first tab 12 abuts against the first tab 12.

[0261] The first current collecting part 41 and the second current collecting part 42 are both in contact with the first tab 12, which can increase the contact area between the current collecting member 40 and the first tab 12, and improve the flow area between the current collecting member 40 and the first tab 12.

[0262] In some embodiments, the surface of the first current collecting part 41 facing the first tab 12 is flush with the surface of the second current collecting part 42 facing the first tab 12, which can improve the uniformity of the force received by the first tab 12, reduce stress concentration, and reduce the risk of local collapse of the first tab 12.

[0263] In some embodiments, the current collecting member 40 is made by stamping a metal plate, and the thinned part of the metal plate is the second current collecting part 42, and the part of the current collecting member 40 that is not stamped is the first current collecting part 41.

[0264] FIG. 11 is a partial cross-sectional view of a battery cell according to some embodiments of the present application.

[0265] Referring to FIG. 11, in some embodiments, the first current collecting part 41 protrudes from the surface of the second current collecting part 42 facing the first tab 12. The surface of the first tab 12 facing the current collecting member 40 is provided with a tab groove 121, and a part of the first current collecting part 41 is accommodated in the tab groove 121.

[0266] Protruding the first current collecting part 41 towards the first tab 12 can increase the thickness of the first current collecting part 41. By providing the tab groove 121, space can be provided for the first current collecting part 41, thereby reducing the space occupied by the first current collecting part 41 and improving space utilization.

[0267] In some embodiments, when assembling the current collecting member 40 and the electrode assembly 10, the first current collecting part 41 extrudes the first tab 12 and forms the tab groove 121. The embodiments of the present application can increase the pressure between the first current collecting part 41 and the first tab 12, improve the stability of the contact between the first current collecting part 41 and the first tab 12, and reduce the resistance.

[0268] In some embodiments, the first current collecting part 41 protrudes from both the surface of the second current collecting part 42 facing the first tab 12 and the surface of the second current collecting part 42 facing away from the first tab 12.

[0269] In the thickness direction Z of the current collecting member 40, the first current collecting part 41 protrudes from both sides of the second current collecting part 42, which can further increase the thickness of the first current collecting part 41.

[0270] In other alternative embodiments, the surface of the first current collecting part 41 facing away from the first tab 12 can also be flush with the surface of the second current collecting part 42 facing away from the first tab 12.

[0271] FIG. 12 is a schematic view of a partial cross-section of a battery cell according to some embodiments of the application.

[0272] As shown in FIG. 12, in some embodiments, the current collecting member 40 includes a protrusion 43 and a third recess 44, the second current collecting portion 42 surrounds the protrusion 43, the protrusion 43 protrudes from a surface of the second current collecting portion 42 facing the electrode terminal 30, and the third recess 44 is recessed from a surface of the second current collecting portion 42 facing the first tab 12 in position corresponding to the protrusion 43. The bottom wall of the third recess 44 is the first current collecting portion 41.

[0273] By providing the protrusion 43 and the third recess 44, the strength of the current collecting member 40 as a whole can be increased, and the deformation of the current collecting member 40 during production and transportation can be reduced. By providing the third recess 44, the first current collecting portion 41 can be spaced apart from the first tab 12, and the heat conducted to the first tab 12 during welding of the first current collecting portion 41 and the electrode terminal 30 can be reduced, so that the risk of deformation and shrinkage of the separator of the electrode assembly 10 due to heat can be reduced, and the reliability of the battery cell 7 can be improved.

[0274] In some embodiments, the protrusion 43 and the third recess 44 are formed by a stamping process.

[0275] In some embodiments, the protrusion 43 includes a side portion 45 surrounding the first current collecting portion 41, and the side portion 45 connects the first current collecting portion 41 and the second current collecting portion 42. The side portion 45 and the first current collecting portion 41 define the third recess 44.

[0276] FIG. 13 is a schematic view of a partial cross-section of a battery cell according to some embodiments of the application.

[0277] Referring to FIG. 13, the current collecting member 40 includes a protrusion 43 and a third recess 44, the second current collecting portion 42 surrounds the protrusion 43, the protrusion 43 protrudes from a surface of the second current collecting portion 42 facing the electrode terminal 30, and the third recess 44 is recessed from a surface of the second current collecting portion 42 facing the first tab 12 in position corresponding to the protrusion 43. The current collecting member 40 further includes a current collecting plate 46 accommodated in the third recess 44, and the current collecting plate 46 is fixed to the bottom wall of the third recess 44. The first current collecting portion 41 includes the current collecting plate 46 and the bottom wall of the third recess 44.

[0278] The current collecting plate 46 can be connected to the bottom wall of the third recess 44 by adhesion, welding, clamping or other processes.

[0279] The thickness of the bottom wall of the third recess 44 can be greater than, equal to or less than the thickness of the second current collecting portion 42.

[0280] The current collector plate 46 can play a protective role when the welding electrode terminal 30 and the bottom wall of the third recess 44 are welded. Even if the bottom wall of the third recess 44 is melted through, the current collector plate 46 can stop the molten liquid and be used for welding, thereby reducing the risk of molten liquid falling. The current collector plate 46 is independently formed with the bottom wall of the third recess 44, which can reduce the difficulty of forming the third recess 44 and the convex portion 43. The current collector plate 46 is accommodated in the third recess 44, which can also improve the space utilization.

[0281] In some embodiments, a part of the first welding portion W is formed on the current collector plate 46. When welding, a part of the current collector plate 46, a part of the connecting portion 33, and a part of the bottom wall of the third recess 44 are melted and form a molten pool, and the molten pool solidifies to form the first welding portion W.

[0282] FIG. 14 is a schematic view of an electrode assembly and a current collecting member of a battery cell according to some embodiments of the present application.

[0283] Referring to FIG. 14, in some embodiments, the first tab 12 is wound to be arranged, and a part of the first tab 12 is bent to form an overlapping region 122 overlapping in the axial direction of the electrode assembly 10, and the overlapping region 122 is welded to the second current collecting portion 42.

[0284] Optionally, the axial direction is parallel to the thickness direction Z.

[0285] The overlapping region 122 of the first tab 12 has a multi-layer structure. Welding the overlapping region 122 to the second current collecting portion 42 can not only reduce the risk of false welding, but also increase the welding area of the first tab 12 and the second current collecting portion 42, thereby improving the overcurrent capacity. The second current collecting portion 42 has a small thickness, which can be deformed to adapt to the overlapping region 122, thereby reducing the gap between the second current collecting portion 42 and the first tab 12 and reducing the risk of false welding.

[0286] For example, the first tab 12 is bent to form the overlapping region 122 by a rubbing process or a smoothing process.

[0287] In the axial direction, the number of layers of the first tab 12 overlapping in the overlapping region 122 is greater than or equal to 2, and optionally, the number of layers of the first tab 12 overlapping in the overlapping region 122 is greater than or equal to 5.

[0288] In some embodiments, a part of the first tab 12 is bent inward in the radial direction of the electrode assembly 10.

[0289] According to some embodiments of the present application, the present application also provides a battery comprising a plurality of battery cells 7 according to any one of the above embodiments.

[0290] According to some embodiments of the present application, the present application also provides a power consuming device comprising the battery cell 7 of any of the above embodiments, the battery cell 7 being configured to provide power for the power consuming device. The power consuming device can be any of the devices or systems mentioned above that use the battery cell 7.

[0291] Referring to FIGS. 5-10, the present application provides a battery cell 7 comprising a housing 20, an electrode assembly 10, an electrode terminal 30, and a current collecting member 40.

[0292] The housing 20 comprises a casing 21 having an opening and an end cap 22 configured to cover the opening. The casing 21 comprises an end wall 211 opposite the end cap 22, and the electrode terminal 30 is disposed insulatively on the end wall 211. At least part of the electrode assembly 10 is accommodated in the casing 21.

[0293] The electrode assembly 10 comprises a main body 11, a first tab 12 extending from one end of the main body 11 facing the electrode terminal 30, and a second tab 13 extending from the other end of the main body 11 away from the electrode terminal 30. The first tab 12 and the second tab 13 are of opposite polarity, the first tab 12 is electrically connected to the electrode terminal 30, and the second tab 13 is electrically connected to the end wall 211.

[0294] The current collecting member 40 is accommodated in the housing 20 and disposed on the side of the first tab 12 facing the electrode terminal 30. The current collecting member 40 comprises a first current collecting portion 41 and a second current collecting portion 42 surrounding the first current collecting portion 41. The first current collecting portion 41 is welded to the electrode terminal 30 and forms a first welding portion W, and the second current collecting portion 42 is welded to the tab and forms a second welding portion. The thickness of the first current collecting portion 41 is greater than the thickness of the second current collecting portion 42.

[0295] The side of the electrode terminal 30 facing the current collecting member 40 is provided with a first recess 31, and the side of the electrode terminal 30 away from the current collecting member 40 is provided with a second recess 32. The bottom surface 311 of the first recess and the bottom surface 321 of the second recess form a connecting portion 33.

[0296] A portion of the first current collecting portion 41 protrudes from the surface of the second current collecting portion 42 facing the electrode terminal 30. At least part of the first current collecting portion 41 is accommodated in the first recess 31 and abuts against the bottom surface 311 of the first recess. The connecting portion 33 is welded to the first current collecting portion 41 and forms the first welding portion W. The first welding portion W is exposed to the second recess 32.

[0297] In the thickness direction Z of the current collecting member 40, the size h1 of the portion of the first welding portion W formed on the first current collecting portion 41 is less than the thickness t1 of the first current collecting portion 41 and greater than the thickness t2 of the second current collecting portion 42.

[0298] The connecting portion 33 is provided with a first through hole 331, the first current collecting portion 41 is provided with a second through hole 412, and the first through hole 331 and the second through hole 412 are oppositely arranged along the thickness direction Z of the current collecting member 40. The battery monomer 7 further comprises a first sealing member 50, at least a part of the first sealing member 50 is arranged in the second recess 32 and is used for sealing the first through hole 331.

[0299] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0300] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell comprising: a case; an electrode terminal provided to the case; an electrode assembly accommodated in the case, the electrode assembly provided with a first tab at one end facing the electrode terminal; a current collecting member accommodated in the case and provided at one side of the first tab facing the electrode terminal, the current collecting member including a first current collecting portion and a second current collecting portion connected to the first current collecting portion, the first current collecting portion welded to the electrode terminal, the second current collecting portion connected to the tab, the first current collecting portion having a thickness greater than a thickness of the second current collecting portion.

2. The battery cell of claim 1, wherein, the second current collecting portion provided around the first current collecting portion.

3. The battery cell of claim 1 or 2, wherein, the first current collecting portion welded to the electrode terminal and forming a first welded portion; in a thickness direction of the current collecting member, a dimension of a portion of the first welded portion formed at the first current collecting portion is less than the thickness of the first current collecting portion.

4. The battery cell of claim 3, wherein, in the thickness direction of the current collecting member, the dimension of the portion of the first welded portion formed at the first current collecting portion is greater than the thickness of the second current collecting portion.

5. The battery cell of any one of claims 1-4, wherein, the second current collecting portion has a higher Brinell hardness than the first current collecting portion.

6. The battery cell of any one of claims 1-5, wherein, the thickness of the first current collecting portion is 1.2 to 3 times the thickness of the second current collecting portion.

7. The battery cell of any one of claims 1-6, wherein, at least a portion of the first current collecting portion protrudes from a surface of the second current collecting portion facing the electrode terminal and abuts against the electrode terminal.

8. The battery cell of any one of claims 1-7, wherein, in the thickness direction of the current collecting member, the second current collecting portion is spaced apart from the electrode terminal.

9. The battery cell of any one of claims 1-8, wherein, one side of the electrode terminal facing the current collecting member is provided with a first recess, at least a portion of the first current collecting portion is accommodated in the first recess and abuts against a bottom surface of the first recess.

10. The battery cell of claim 9, wherein, in the thickness direction of the current collecting member, a height of the first current collecting portion protruding from a surface of the second current collecting portion facing the electrode terminal is 1.2 to 2 times a depth of the first recess.

11. The battery cell of claim 9 or 10, wherein, in a radial direction of the current collecting member, a gap is provided between the first current collecting portion and a side surface of the first recess.

12. The battery cell of any one of claims 1-11, wherein, one side of the electrode terminal facing away from the current collecting member is provided with a second recess, the electrode terminal includes a connecting portion at a bottom of the second recess, the connecting portion welded to the first current collecting portion and forming a first welded portion, the first welded portion exposed to the second recess.

13. The battery cell of claim 12, wherein, one side of the electrode terminal facing the current collecting member is provided with a first recess, the connecting portion formed between a bottom surface of the first recess and a bottom surface of the second recess; at least a portion of the first current collecting portion is accommodated in the first recess.

14. The battery cell of claim 13, wherein, the first current collecting portion has a top surface abutting against the bottom surface of the first recess; in the thickness direction of the current collecting member, the bottom surface of the second recess and the top surface at least partially overlap, and a projection of an outer periphery of the bottom surface of the second recess is located within a projection of the top surface. 15.The battery cell of claim 14, wherein a diameter of the top surface is greater than a diameter of the bottom surface of the second recess; a difference in diameter between the bottom surface of the first recess and the top surface is less than a difference in diameter between the top surface and the bottom surface of the second recess.

16. The battery cell of any one of claims 12-15, wherein, a thickness of the connecting portion is 1 to 3 times a thickness of the first current collecting portion.

17. The battery cell of any one of claims 12-16, wherein, The connecting portion is provided with a first through hole, and the first current collecting portion is provided with a second through hole, the first through hole and the second through hole are oppositely arranged along the thickness direction of the current collecting member; The battery monomer further comprises a first sealing member, at least part of the first sealing member is arranged in the second recess and is used for sealing the first through hole.

18. The battery cell of claim 17, wherein, In the radial direction of the current collecting member, the hole wall of the first through hole protrudes inwardly from the hole wall of the second through hole; The first sealing member comprises a first sealing portion, a second sealing portion and a third sealing portion, the first sealing portion is located outside the connecting portion, the second sealing portion is located inside the connecting portion and is at least partially accommodated in the second through hole, and the third sealing portion is accommodated in the first through hole and connects the first sealing portion and the second sealing portion. In the thickness direction of the current collecting member, part of the connecting portion is located between the first sealing portion and the second sealing portion.

19. The battery cell of claim 18, wherein, In the radial direction of the current collecting member, the second sealing portion is arranged in a spaced manner with the hole wall of the second through hole.

20. The battery cell of any one of claims 1-19, wherein, The surface of the first current collecting portion facing the first tab is in abutment with the first tab, and the surface of the second current collecting portion facing the first tab is in abutment with the first tab.

21. The battery cell of claim 20, wherein, The surface of the first current collecting portion facing the first tab is flush with the surface of the second current collecting portion facing the first tab.

22. The battery cell of claim 20, wherein, The first current collecting portion protrudes from the surface of the second current collecting portion facing the first tab; The surface of the first tab facing the current collecting member is provided with a tab groove, and part of the first current collecting portion is accommodated in the tab groove.

23. The battery cell of claim 1, wherein, The current collecting member comprises a protruding portion and a third recess, the second current collecting portion surrounds the protruding portion, the protruding portion protrudes from the surface of the second current collecting portion facing the electrode terminal, and the third recess is in position correspondence with the protruding portion and is recessed relative to the surface of the second current collecting portion facing the first tab; The bottom wall of the third recess is the first current collecting portion.

24. The battery cell of claim 1, wherein, The current collecting member comprises a protruding portion and a third recess, the second current collecting portion surrounds the protruding portion, the protruding portion protrudes from the surface of the second current collecting portion facing the electrode terminal, and the third recess is in position correspondence with the protruding portion and is recessed relative to the surface of the second current collecting portion facing the first tab; The current collecting member further comprises a current collecting plate accommodated in the third recess, and the current collecting plate is fixed to the bottom wall of the third recess; the first current collecting portion comprises the current collecting plate and the bottom wall of the third recess.

25. The battery cell of any one of claims 1-24, wherein, The shell comprises a shell body and an end cover, the shell body has an opening, and the end cover covers the opening; The shell comprises an end wall opposite to the end cover, and the electrode terminal is arranged on the end wall.

26. The battery cell of any one of claims 1-25, wherein, The first tab is arranged in a winding manner, part of the first tab is bent and forms an overlapping area overlapping in the axial direction of the electrode assembly, and the overlapping area is welded with the second current collecting portion.

27. A battery comprising a plurality of battery monomers according to any one of claims 1-26.

28. An electrical device comprising the battery according to claim 27, wherein the battery is used to provide electrical energy.

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